Excess Ti Research Articles

Barium, Lithium and Titanium Content in Herbs of Mid-Field Wet Depressions in East-Central Poland

This paper presents the results of research on the Ba, Li and Ti content in six species of herbs sampled from mid-field wet depressions and from the soil. These temporary flooded depressions were surrounded by arable crops, permanent grassland and shrubby vegetation. The research area was located in the eastern part of the Mazovian Voivodeship, east-central Poland. The following plants were used in the experiment: corn mint (Mentha arvensis L.), purple marshlocks (Comarum palustre L.), silverweed (Potentilla anserina L.), yarrow (Achillea millefolium L.), yellow loosestrife (Lysimachia vulgaris L.) and gypsy-wort (Lycopus europaeus L.). The Li, Ba and Ti content of plants, bottom sediment and soil was determined by the ICP-AES method after previous dry mineralization. Of the six herb species, Mentha arvensis L. was with the greatest accumulation potential of the chemical elements. However, no excessive Ba, Li and Ti content was found in herbs growing at different distances from arable fields, permanent grassland and shrubby vegetation. The highest Ba content was found in periodically flooded soil (zone II), while the highest amounts of Li and Ti were recorded in non-flooded soil (zone III).

Formation of silicide layers on a Ti-46Al-8Ta alloy in pack cementation and diffusion couple experiments

This work compares silicide layers grown on Ti-46Al-8Ta (at.%) substrates in pack cementation and in diffusion couple experiments at elevated temperatures. Based on preliminary experiments showing Kirkendall porosity at the coating/substrate interface, a micrometric Ti-10%Si interlayer was deposited by magnetron sputtering prior to siliconizing treatments to prevent excessive Ti diffusion from the substrate. In both types of experiments, the diffusion zone was multi-layered and consisted of Ti/Ta silicides in the outer part and Ti/Ta aluminides in the inner part next to the interface with the alloy. Significant differences were found in the overall thickness and thicknesses of the individual layers. Kinetics of layer growth was followed by thickness measurements. Although inward diffusion of silicon was the dominant mechanism of coating formation, other concurrent processes evidently contributed to the development of the characteristic microstructural features and to the observed differences in thickness.

Preparation of porous TiNi-Ti alloy by diffusion sintering method and study of its composition, structure and martensitic transformations

The study demonstrates a method for controlling not only the phase composition but also the atomic composition of TiNi matrix in porous TiNi-Ti alloys developed for biomedical uses as implants. The alloys were obtained from TiNi powder which was sintered with Ti powder added at as much as 0–10 at%. The structure, phase and chemical composition of the produced TiNi-Ti alloys was investigated with respect to the amount of Ti added into the material. It is shown that in the sintered product containing 5 at% and more of Ti additive, the composition of its TiNi matrix becomes close to equiatomic (with Ti:Ni atomic ratio ~1), and the excessive Ti precipitates as secondary phases Ti2Ni and Ti3Ni4. In parallel, with increase in Ti additive from 0–10 at%, the structure of the precipitating Ti2Ni type phases changes its morphology from separate spherical or pyramidal precipitates to large dendritic formations. The direct martensitic transformation from austenite to martensite in all the samples was found to proceed in two stages and through the R-phase (B2→R→B19′). Thermoresistive analysis demonstrated that TiNi-Ti samples with 5 and more at% of Ti had their characteristic starting temperature of martensite transition stabilizing at ~57 °C (330 K). This implies that the sample with 5 at% of Ti additive exhibited desired martensite transition temperatures, while containing a minimum concentration of secondary-phase precipitates in its matrix which deteriorate its properties. Thus, for the first time, we show that a very simple preparation approach based on sintering powders of TiNi and Ti is capable of producing porous TiNi-Ti alloys with properties optimized for fabricating bone implants.

Co-sputtered Pt/Ti alloy cathode for low-temperature solid oxide fuel cell

One of the effective strategies to enhance the activity and stability of the Pt-based catalysts in low-temperature solid oxide fuel cells (LT-SOFCs) is modifying the electronic structure and reducing the surface energy of Pt by transition metal alloying. Herein, co-sputtered Pt/Ti alloy cathodes for LT-SOFC with varying Pt/Ti compositional ratios (Ti 0–26 at%) are fabricated and tested. The cell constructed with the optimal (6–11 at% Ti) Pt/Ti alloy cathode shows five times lower degradation rate in activation resistance compared to a pure Pt cathode at 450 °C, resulting in a 33% enhancement in the maximum power density after 2 h of operation. We show that the performance enhancement of the Pt/Ti alloy cathode at elevated temperature is due to the formation of a catalytically active and thermally stable Pt3Ti alloy phase, in which coarsening is effectively prevented as opposed to its pure Pt counterpart. Moreover, we demonstrate that Pt/Ti alloy cathodes with excessive Ti content (≥ 19 at%) suffer from the formation of a nonreactive TiO2 surface upon oxygen exposure at elevated temperature, which causes higher activation resistance.

Introducing a 3D-SiO2-fiber interlayer for brazing SiC with TC4 by AgCuTi

Brazing SiC and TC4 involves excessive Ti diffused from TC4 and high residual stress in the joint. In order to achieve a high-quality joint between SiC and TC4, a new interlayer braided by short fibers in three dimensions (3D-SiO2-fiber) was introduced to assist in brazing. The 3D-SiO2-fiber, with loose and porous structure, can guarantee abundant SiO2 fibers evenly distribute in the joint. Furthermore, extensive Ti element was consumed by SiO2 fibers. Then enormously and uniformly distributed TiSi2, TiCu2, TiSi and α-Ti particles were formed at the joint. Finally, residual stress was released and the shear strength of the joint increased to 40 MPa.

Ultrasonic treatment for the refinement of brittle CaZn13 phases in a biomedical Zn-Cu-Ca alloy

Ultrasonic treatment (UST) for the refinement of long, coarse and branched dendrites of CaZn13 phases in Ca containing Zn-Cu-Ca alloys has been investigated. UST applied in the L + CaZn13 region led to a significant reduction in the average size of CaZn13 phases from larger than 150 μm to < 20 μm. Longer UST time of 7 min from 620 °C to 420 °C at a cooling rate of 0.5 °C/s resulted in excessive Ti dissolution from the sonotrode and formed primary Zn-Ti phases. Increasing the cooling rate to 4.0 °C/s, reducing the UST time to 2 min and the temperature range from 620 °C to 450 °C followed by immediate pouring offered the best refinement with a lower concentration of Ti.

Poorly crystallized Bi(Mg,Zr,Ti)O3 lead-free thin films for energy-storage applications

Improving energy storage density and efficiency is the ultimate goal of dielectric materials used in ceramic capacitors. Among different dielectric materials, dielectrics in thin film state own superior energy performances due to less defects compared with ceramic. Herein, we report an optimized lead-free Zr-modified BiMg0.5Zr0.04Tix-0.04O3 composition with enhanced energy storage behavior via microstructural engineering. Rapid annealing can result in poorly crystallization in the film matrix confirmed by grazing incident X-ray diffraction GIXRD. The excess Ti source can effectively increase polarization and dielectric breakdown till to 97.0 μC/cm2 and 3403 kV/cm at x = 0.775, respectively. The optimized energy properties can be achieved at x = 0.775 with a high recoverable energy storage density Wreco of 87.8 J/cm3 and an efficiency η of 50%, indicative of excellent stability of storing electricity for the applications of pulse power electronics.

Improved Performance of InGaZnO Thin-Film Transistor With Ti Incorporation Into La2O3 Gate Dielectric

The effects of Ti incorporation in La2O3 gate dielectric on the electrical characteristics of amorphous InGaZnO thin-film transistor are studied. Compared to the control sample with La2O3 gate dielectric, the device performance can be significantly improved with an appropriate Ti dose. Accordingly, the sample with a Ti/(Ti+La) ratio of 6.7% presents a high saturation mobility of 28.1 cm2V−1s−1, small subthreshold slope of 0.17 V/dec, large on/off current ratio of $7.2\times 10$ 7, and acceptable hysteresis. We attribute such an improvement to the passivation of the defect states at/near the La2O3/InGaZnO interface as well as the enhancement of moisture resistance of La2O3 film due to Ti incorporation. However, excessive Ti incorporation leads to device degradation, which is due to more oxygen vacancies generated in gate dielectric.

Enhancement of boron removal from metallurgical-grade silicon by titanium addition during slag refining

The effects of titanium addition (0 wt.%, 0.2 wt.%, and 0.5 wt.%) on the boron removal from metallurgical-grade silicon during slag refining have been studied. According to the findings, the addition of Ti improved the removal of 92.5 wt.% B with 0.5 wt.% Ti addition compared to 79.4 wt.% B removal without Ti addition. Furthermore, acid leaching reduced excess Ti to 27 ppmw.

Unveiling the interplay between induced native defects and room temperature magnetic ordering in titanium deficient disordered-TiO2 nanoparticles

Understanding the origin of magnetic ordering in an undoped semiconductor with native defects is an open question, which is being explored actively in research. In this investigation, the interplay between magnetic ordering and excess induced native defects in undoped anatase TiO2 nanoparticles is explained using an experimental and theoretical approach. It is demonstrated that structurally disordered TiO2 nanoparticles with a high concentration of native defects such as titanium interstitials and oxygen vacancies are synthesized using controlled atmospheric rapid cooling (i.e. quenching) process. The structural disorders in the lattice have been examined using various spectroscopic and microscopic analyses revealed the existence of Ti deficiency in both pristine and quenched TiO2 nanoparticles. A possible origin of magnetic ordering in titanium deficient anatase TiO2 system is elucidated based on first-principle calculations. It was found that the overall magnetic moment of Ti deficient TiO2 system is determined by the distance between Ti interstitials and its neighboring vacancies (i.e. either V Ti or V Os). However, quenched TiO2 nanoparticles possess excess Ti interstitials, Ti and O vacancies and therefore the net magnetic moment of the system is reduced due to anti-ferromagnetically coupled neighboring Tilattice ions.

Effect of Carbides and γ/γ' Eutectic on Crack Initiation and Propagation in Ni-based Superalloy

The Ni-based Udemit720Li superalloy tends to form large γ/γ' eutectic on grain boundaries (GBs) during solidification due to the addition of excessive Al and Ti elements, which provides convenience to study the effect of carbide and γ/γ' eutectic on crack initiation and propagation during tensile process. In this paper, Udemit720Li superalloy samples were prepared by induction melting casting method, arc melting and suction casting method. The microstructure, tensile properties and mechanism of crack initiation and propagation in Ni-based superalloy fabricated by two methods are investigated. The results exhibit γ/γ' eutectic accelerates the stress concentration at GB and thus leads to premature fracture failure. The samples with grain-boundary eutectic have higher strain hardening rate, but their cumulative and local misorientations are lower. For samples without eutectic at GB, the primary crack initiates at grain-boundary carbide along GB and extends along GB or into grain matrix, and exhibits better deformation performance and dislocation storage capacity within grains.

Effect of Ta and Ti on Modified Reduced Activation Ferritic/Martensitic Steels with a Thermo‐mechanical Control Process

Modified reduced activation ferritic/martensitic steels with different amounts of Ta and Ti are fabricated with a thermo‐mechanical control process (TMCP). TMCP greatly enhances the refinement of both the precipitates and the martensite matrix. In addition, an increase in the dislocation density is achieved. The modified steels show excellent comprehensive mechanical properties compared with traditional reduced activation ferritic/martensitic steels. In addition, under the conditions of the TMCP, the effects of Ta and Ti on the microstructure and properties are analyzed. Simply increasing the amounts of Ta and Ti does not increase the phase fraction of MX, which is quite different from that derived from equilibrium thermodynamics theory or the typical hot rolling process for traditional reduced activation ferritic/martensitic steels. Without a high enough nucleation rate for MX, the excess Ta and Ti, which are not consumed by the formation of MX, promotes the formation of proeutectoid ferrite. This decreases the impact on toughness significantly. Herein, preliminary guidance is offered for a comprehensive design with a combination of both composition and rolling processing modification for the production of reduced activation ferritic/martensitic steels.

Modulation of the electric and magnetic properties by Ti non-stoichiometry in 0.70BiFeO3-0.30BaTixO3 ceramics

The modulation of the structure and dielectric, ferroelectric, and magnetic properties by Ti non-stoichiometry in 0.70BiFeO3-0.30BaTixO3 (BF30BT-x, x = 0.85–1.15) ceramics was studied systematically. In Ti-rich samples, excessive Ti mainly exists in the form of an impurity Aurivillius phase, and so except that the impurity phase reduces the resistance, the structure, morphology, Curie temperature (TC ∼ 390 °C), and ferroelectricity in Ti-rich ceramics are similar to those in stoichiometric ceramics (BF30BT-1.00). In Ti-poor samples, the appropriate Ti-poor concentration appears in the BF30BT-0.90 ceramic, and the structure becomes the coexistence of the rhombohedral phase and the pseudo-cubic phase (R+PC). The ferroelectric phase transition becomes a frequency-independent normal phase transition, and TC is greatly increased (553 °C). The hysteresis loop becomes more saturated, and a large internal bias field (Ei = 4.5 kV/cm) appears. For magnetic properties, all samples display a weak ferromagnetic nature, and as x increases, Mr and Mmax increase nearly linearly.

The superior performance of dichloromethane oxidation over Ru doped sulfated TiO2 catalysts: synergistic effects of Ru dispersion and acidity

In this work, modified Ru/Ti catalysts with support sulfation by the introduction of solid superacid Ti(SO4)2 were employed for the catalytic combustion of dichloromethane (DCM). The experimental results showed that the optimal Ru/TiS0.05 sample yielded a near 100% DCM conversion at 275 °C, which was almost 30% higher than that of the pristine Ru/Ti catalyst. After a series of sample characterizations, it was found that there existed strong interactions between Ru species and sulfated TiO2 support, which would improve the dispersion of Ru species, thereby generating more active sites for DCM deep oxidation. Furthermore, the enhanced acidity derived from sulfation modification would facilitate DCM dissociation, and the generation of Brønsted acidic sites improved HCl selectivity. As such, both the enhancements in acidity and Ru dispersion after sulfation modification resulted in its superior performance of DCM catalytic abatement. Moreover, excessive Ti(SO4)2 addition would lead to the blockage of the pore structure and significantly decrease in the reducibility of the catalyst, leading to the loss of the activity.

Influence of Ti doping on microstructure and electrochemical performance of LiNi0.5Mn1.5O4 cathode material for lithium-ion batteries

LiNi0.5Mn1.5O4 cathode material has been synthesized by a combined coprecipitation-hydrothermal method followed by high-temperature calcination. Ti doping was achieved via acetic acid glacial assisted sol-gel method by using titanium(IV) butoxide as Ti source. The effects of different Ti doping contents on the structure, morphology and electrochemical properties of LiNi0.5Mn1.5O4 materials were systematically investigated. The as-synthesized samples were characterized by XRD, FT-IR, SEM, TEM, XPS, EIS and constant-current charge/discharge test. It is found that although Ti doping can effectively inhibit the formation of LixNi1-xO impurity phase, excessive Ti doping results in the appearance of Li2TiO3 secondary phase. SEM observation shows that Ti doping can improve the crystallinity of particles, and particle size shows a gradual increasing trend with Ti doping content. LiNi0.5Mn1.5O4 material doped with 3% Ti shows high phase purity and crystallinity, appropriate Mn3+ content and particle size with uniform distribution, thereby leading to its optimal electrochemical performance. Its discharge capacity at 10 C rate can reach 127.3 mA h g−1, and capacity retention rate can reach 91.7 % after 200 cycles at 1C and 25 °C. Post-mortem analysis shows that appropriate Ti doping can efficiently ameliorate electrolyte decomposition and other side reactions, thus leading to the formation of thinner SEI/CEI layer on electrode surface, and then better cycling performance achieved.

Investigation of Microstructure of Al-5Ti-0.62C System and Synthesis Mechanism of TiC.

Al-Ti-C master alloys have been widely investigated by various researchers. However, their refining effectiveness is still severely compromised by the preparation process. In this work, the aluminum melt in-situ reaction was carried out to synthesize the Al-5Ti-0.62C, and its refining performance was estimated. The thermodynamics calculation and differential scanning calorimeter experiment were used to investigate the synthesis mechanism of TiC. Quenching experiment was conducted to explore phase and microstructure transformation of the Al-5Ti-0.62C system. The results show that the main phases of Al-5Ti-0.62C master alloys are α-Al, Al3Ti, and TiC and it has a positive effect on commercial pure aluminum refining. Commercial pure aluminum is completely refined into the fine equiaxed structure by adding 0.3% Al-5Ti-0.62C master alloy. TiC particles mainly distribute in the grain interior and grain boundaries. The excess Ti came from the dissolution of Al3Ti spreading around TiC and finally forming the Ti-rich zone to promote the nucleation of α-Al. The experiments certified that TiC was formed by the reaction between solid C and excess Ti atoms. The main reactions in the Al-5Ti-0.62C system were that solid Al is transferred into liquid Al, and then liquid Al reacted with solid Ti to form the Al3Ti. At last, the release of a lot of heat promotes the formation of TiC which formed by the Ti atoms and solid C.

The effect of Ti on the microstructure and mechanical properties of (Ti + Mg3Sb2)/Mg composites

In the present research work, (titanium (Ti) + magnesium antimonide (Mg3Sb2)/magnesium (Mg) composites with Ti contents of 0, 5%, 10%, and 15% (mass fraction, %) were fabricated by powder metallurgy. The effect of different Ti contents on the microstructure and mechanical properties of (Ti + Mg3Sb2)/Mg composites was investigated. The results show that the volume of Mg3Sb2 compounds can be significantly refined and the distribution uniformity of Mg3Sb2 compounds can be improved by adding an appropriate amount of Ti. Part of Sb reacts with Ti in situ to form TiSb2 compounds at the periphery of Ti particles. However, the reaction is not sufficient, and there is still the remaining Ti distribution in composites. Both Ti particles and TiSb2 compounds form (Ti + TiSb2) microstructures, which have different degrees of agglomeration with the increase of Ti contents in composites. The appropriate amount of Ti can improve the mechanical properties of the composite, but excessive Ti can reduce the tensile strength of the composite.

Microstructure and phase composition of the Nb-Si based in-situ composite from plasma spheroidized powder

Mechanical alloying with subsequent plasma spheroidization is a novel technological route to produce the new powder materials for additive manufacturing technologies, such as selective laser melting and direct laser fabrication. Nb-25Ti-2Cr-2Al-2Fe-16Si (at.%) powder synthesized by mechanical alloying and plasma spheroidization. The spheroidized powder with uniformly chemical elements distribution was sieved for 71–125 μm and used for spark plasma sintering. The sintered specimen consists of 5 phases – continuous Nbss, with dispersed Nb5Si3, NbFe4Si, Ti5Si3, and Ti. The formation of the Ti and Ti5Si3 phases is associated with an excess Ti content in the chemical composition, which was previously suppressed by rapid cooling during plasma spheroidization.

Changes in the body, glaze and enamel compositions of early Meissen porcelain, 1723–c.1740

The evolution of early Meissen body, glaze and colorant compositions is examined using X‐ray fluorescence spectroscopy (XRF) measurements on three artefacts that can be accurately dated to the period 1723–c.1740. The results are interpreted based on recipes recorded in the earliest documents of the Meissen archives. The pure Aue kaolinite contains low levels of Ti and can be distinguished from secondary clays, for example, clay from Colditz. The excess Ti in the glaze versus the body reported earlier and confirmed by the present authors is explained by the exclusive use of Colditz clay for the glaze, as described in the recipes before 1730, providing a terminus ante quem for Meissen porcelain exhibiting this particular asymmetry. After 1730, the presence of elevated Ti in the body could serve as a marker for the experimental admixture of clays to Aue kaolinite to alter its properties. Based on the detection of As, Ba and Bi, it is suggested that smalt from Erzgebirge was the colorant for blue enamels until at least 1725.

Intrinsic interfacial van der Waals monolayers and their effect on the high-temperature superconductor FeSe/SrTiO3

The sensitive dependence of monolayer materials on their environment often gives rise to unexpected properties. It was recently demonstrated that monolayer FeSe on a SrTiO$_3$ substrate exhibits a much higher superconducting critical temperature T$_C$ than the bulk material. Here, we examine the interfacial structure of FeSe / SrTiO$_3$ and the effect of an interfacial Ti$_{1+x}$O$_2$ layer on the increased T$_C$ using a combination of scanning transmission electron microscopy and density functional theory. We find Ti$_{1+x}$O$_2$ forms its own quasi-two-dimensional layer, bonding to both the substrate and the FeSe film by van der Waals interactions. The excess Ti in this layer electron-dopes the FeSe monolayer in agreement with experimental observations. Moreover, the interfacial layer introduces symmetry-breaking distortions in the FeSe film that favor a T$_C$ increase. These results suggest that this common substrate may be functionalized to modify the electronic structure of a variety of thin films and monolayers.